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Clinical Anaesthesiology
Qiu Wei FanAssociate Professor
Department of AnaesthesiologyRui Jin Hospital
Shanghai Second Medical University
General Anaesthesia
Classification of General Anaesthesia Methods
Inhalation anaesthesiaIntravenous anaesthesiaIntramuscularlyRectallyOrallyBalanced anaesthesia
Clinical PharmacologyInhalational anaesthetic agents
Agent MAC% Vapor Pressure Blood/Gas Partition Nitrous oxide 105 - 0.47 Halothane 0.74 243 2.4 Enflurane 1.68 175 1.9 Isoflurane 1.15 240 1.4 Desflurane 6.0 681 0.42
Clinical PharmacologyIntravenous anaesthetic agents
Agent Induction dose (mg·kg-1)
Thiopentone 3-5 Methohexitone 1-1.5 Etomidate 0.3 Propofol 1.5-2.5 Ketamine 2
Clinical PharmacologyDrugs used to supplement anaesthesia
AnalgesicsOpioid agonists Natural opium alkaloids: Morphine,Codeine Semisynthetic opium alkaloid: Diamorphine Synthetic opioids:Pethidine, Fentanyl, Alfent
anil, Sufentanil, RemifentanilPartial opioid agonists Buprenorphine
Clinical PharmacologyDrugs used to supplement anaesthesia
Opioid agonist/antagonists PentazocineOpioid antagonists Naloxone
Clinical PharmacologyMuscle Relaxants
Neuromuscular blocking agents are dividedinto two classes:
Depolarizing Nondepolarizing
Clinical PharmacologyMuscle Relaxants
Depolarizing Short-acting Succinylcholine Decamethonium
Nondepolarizing Long-acting Tubocurarine Metocurine doxacurium Pancuronium Pipecurium Intermediate-acting Atracurium Vecuronium Short-acting Mivacurium
Clinical PharmacologyDrugs affecting the autonomic nervous
system Sympathomimetic drugs Adrenaline(low-α,β1+2)(higher- α) Isoprenaline(β1+2) Noradrenaline(α,β1 ) Phenylephine(α) Dopamine (low-δ,moderate-δ ,β1+2, mode
ratehigh-α,β1 ) Dobutamine(β1 )
The practical conduct of anaesthesia
Preparation for anaesthesia Equipment for monitoring The anaesthetic machine Equipment required for trache
al intubation
Anaesthetic apparatusThe anaesthesia machine
Gas inlets & pressure regulators Oxygen pressure failure devices & oxygen
flush valves Flow control valves Flowmeters & spirometers Vaporizers Vantilators & disconnect alarms Waste gas scavengers Humidifiers & nebulizers Oxygen analyzers
Airway management equipment
Oral & Nasal airway Mask Endotracheal tube Rigid laryngoscopes Flexible fiberoptic laryngosco
pes
Equipment required for tracheal intubation Correct size of laryngosco
pe and spare Tracheal tube of correct si
ze + an alternative smaller size
Tracheal tube connector Wire stilette Gum elastic bougies Magill forceps Cuff-inflating syringe Artery forceps
Securing tape or bandage Catheter mount Local anaesthetic spray Cocaine spray/gel for nas
al intubation Tracheal tube lubricant Throat packs Anaesthetic breathing sys
tem and face masks-tested with oxygen to ensure no leaks present
Induction of Anaesthesia
Inhalational induction Intravenous induction
Inhalational induction agents
Sevoflurane Desflurane
Induction of anaesthesiaIndications for inhalational induction
Young children Upper airway obstruction Low airway obstruction with fore
ign body Bronchopleural fistula or empye
ma No accessible veins
Induction of anaesthesia Difficulties and complications
Slow induction of anaesthesia Problems particularly during stage
2 Airway obstruction, bronchospasm Laryngeal spasm, hiccups Environmental pollution
Intravenous inductionDoses of the intravenous agents
Agent Induction dose (mg·kg-1)
Thiopentone 3-5 Methohexitone 1-1.5 Etomidate 0.3 Propofol 1.5-2.5 Ketamine 2
Intravenous induction Complications and difficulties
Regurgitation and vomiting Intra-arterial injection of thiopentone Perivenous injection Cardiovascular depression Respiratory depression Histamine relea
se Porphyria Other complications
Maintenance of anaesthesiaInhalation anaesthesia with spontaneous ventilation
Conduct Minimum alveolar concentration
(MAC): MAC is the minimum alveolar concentration of an inhaled anaesthetic agent, which prevents reflex movement in response to surgical incision in 50 % of subjects.
Clinical PharmacologyInhalational anaesthetic agents
Agent MAC% Vapor Pressure Blood/Gas Partition
Nitrous oxide 105 - 0.47
Halothane 0.74 243 2.4
Enflurane 1.68 175 1.9
Isoflurane 1.15 240 1.4
Desflurane 6.0 681 0.42
Signs of anaesthesia
Stage 1(Stage of analgesia): From start of induction of anaesthesia to loss of consciousness.
Stage 2 (Stage of excitement): From loss of consciousness to beginning of regular respiration.
Stage 3 (Surgical anaesthesia): From the beginning of regular respirationto respiratory arrest.
Signs of anaesthesia The stage 3 is divided into four planes.
Plane 1: From the onset of regular breathing to the cessation of eyeball movements.Plane 2: From the cessation of eyeball movements to the beginning of intercostal paralysis.Plane 3: From the beginning of intercostal paralysis to the completion of intercostal paralysis.Plane 4: From completion of intercostal paralysis to diaphragmatic paralysis.
Signs of anaesthesia
Stage 4: Stage of impending respiratory and circulatory failure (Medullary paralysis), from the onset of diaphragmatic paralysis to cardiac arrest.
Inhalation anaesthesia with spontaneous ventilation Complications and difficulties
Airway obstruction Laryngeal spasm Bronchospasm Malignant hyperthermia Raised intracranial pressure (I
CP) Atmospheric pollution
Delivery of inhalational agents-airway maintenance
Use of the facemask Use of the laryngeal mask air
way (LMA) Use of the oropharyngeal airw
ay Tracheal intubation
Use of the laryngeal mask airway (LMA) Indications
Provide a clear airway without the need for the anaesthetist’s hands to support a mask.
Avoid the use of tracheal intubation during spontaneous ventilation.
In a case of difficult intubation to facilitate subsequent insertion of a tracheal tube either via the LMA or after use of a gum elastic bougie.
Use of the laryngeal mask airway (LMA) Contraindications
A patient with a “full stomach” or with any condition leading to delayed gastric emptying,
A patient in whom regurgitation of gastric contents into the esophagus is possible,
Where surgical access is impeded by the cuff of the LMA.
Tracheal intubationIndications
Provision of a clear airway, An ‘unusual’ position, Operations on the head and neck, Protection of the respiratory tract, During anaesthesia using IPPV and muscle r
elaxants To facilitate suction of the respiratory tract During thoracic operations
Tracheal intubation Contraindications
Few
Anaesthesia for tracheal intubation
Inhalational technique for intubation
Relaxant anaesthesia for intubation
Anaesthesia for tracheal intubation
Oral-tracheal intubation Nasotracheal intubation Flexible fiberoptic nasotracheal in
tubation
Complications of intubationDuring laryngoscopy and intubation
MaipositioningEasophageal intubationEndobronctrial intubationLaryngeal position
Airway trauma Tooth damage Lip, tongue or mucosal laceration Sore throat Dislocated mandible
Complications of intubationDuring laryngoscopy and intubation
Retropharyngeal dissection Physiologic reflexes
Hypertension, TachycardiaIntracranial hypertentionIntraocular hypertension
Laryngospasm Tube malfunction Cuff perforation
Complications of intubation While the tube is in place
Malposition Unintentional e
xtubation Endobrochial in
tubation Laryngeal cuff p
osition
Airway trauma Mucosal
inflammation and ulceration
Excoriation of nose
Tube malfunction Ignition Obstruction
Complications of intubation Following extubation
A) Airway trauma Edema and stenosis
(glottic, subglottic, or tracheal )
Hoarseness (vocal cord granuloma or paralysis )
Laryngeal malfunction and aspiration
B) Physiologic reflexesLaryngospasm
Relaxant anaesthesiaIndications for relaxant anaesthesia
Major abdominal, intraperitoneal, thoracic, intracranial operations
Prolonged operations in which spontaneous ventilation would lead to respiratory depression
Operations in a position in which ventilation is impaired mechanically
Clinical PharmacologyMuscle Relaxants
Depolarizing Short-acting Succinylcholine Decamethonium
Nondepolarizing Long-acting Tubocurarine Metocurine doxacurium Pancuronium Pipecurium Intermediate-acting Atracurium Vecuronium Short-acting Mivacurium
Reversal of relaxation
Residual neuromuscular block is antagonized with neostigmine 2.5-5mg (0.05-0.08mg·kg-1 in children). Atropine 1.2mg or glycopyrronium 0.5mg counteracts the muscarinic side effects of the anticholinesterase and may be given before, or with, neostigmine.
Conduct of extubation
Coughing Resistance to the
presence of the tracheal tube
Complications of tracheal extubation
Laryngeal spasm Regurgitation
Emergence and recovery
Testing hand grip tongue protrusion Lifting the head from the
pillow in response to command
Monitoring during anaesthesia
Cardiac monitors Arterial blood
pressure Noninvasive
arterial blood pressure
Invasive arterial blood pressure monitoring
Electrocardiography Central venous
catheterization Pulmonary artery
catheterization Cardiac output
Noninvasive arterial blood pressure monitoringTechnique
Palpation Doppler probe Auscultation Oscillometry Plethysmography Arterial Tonometry
Selection of artery for cannulation Radial artery Brachial artery Ulnar artery femoral artery Dorsalis pedis Posterior tibial artery Axillary artery
Invasive arterial blood pressure monitoringComplications
Hematoma Vasospasm Arterial thrombosi
s Embolization of ai
r bubbles or thrombi
Skin necrosis overlying the catheter
Nerve damage Infection
Unintentional intra-arterial drug injection
Monitoring during anaesthesiaRespiratory system monitoring
Precordial & easophageal stethoscope Breathing circuit pressure & exhaled tid
al volume Pulse oximetry End-tidal carbon dioxide analysis Transcutaneous oxygen & carbon dioxi
de monitors Anaesthetic gas analysis
Monitoring during anaesthesiaNeurologic system monitors
Electroencephalography Evoked potential
Monitoring during anaesthesiaMiscellaneous monitors
Temperature Urine output Peripheral nerve
stimulation
Complications during anaesthesiaArrhythmias Bradycardia Tachycardia Atrial arrhythmias Ventricular arrhythmias (Pre
mature ventricular contractions (PVCs))
Heart block
Complications during anaesthesiaHypotention Decreased cardiac output: Decreased venous return Myocardial Vasodilation Drugs Septicaemia Hypovolaemia Haemorrhage
Complications during anaesthesia Hypertension Hypervolaemia Myocardial ischaemia Cardiac arrest Embolism Hypoxaemia
Complications during anaesthesia Hypercapnia Hypocapnia Respiratory obstruction Intubation problems Aspiration of ga
stric contents Hiccups Adverse drug effects
Complications during anaesthesia Malignant hyperthermia (MH) Hyperthermia Hypothermia Acute intermittent porphyria(AIP) Awareness Injury
Questions
What is the meaning of MAC? What are the Guedel’s classic signs of anaesth
esia? How many methods for the anaesthetists use t
o maintain the airway? What are they?
Questions
What are the indications for tracheal intubation?
What are the complications during general anaesthesia?
Any Question?
THANK YOU !